CN101903640A

CN101903640A - Piezo intensifier fuel injector and engine using same

Info

Publication number: CN101903640A
Application number: CN200880121579XA
Authority: CN
Inventors: H·金; D·吉布森; M·索马尔斯
Original assignee: Caterpillar Inc
Current assignee: Caterpillar Inc
Priority date: 2007-10-19
Filing date: 2008-10-10
Publication date: 2010-12-01
Anticipated expiration: 2028-10-10
Also published as: US8082902B2; CN101903640B; DE112008002785T5; WO2009051675A1; US20090101112A1

Abstract

A common rail (18) fuel injection system includes a piezo intensifier fuel injector (14) that includes a plurality of components. Among these are a needle valve member (60), an intensifier piston (80), a first piezo stack electrical actuator (50) and a second piezo stack electrical actuator (51). These components have a first configuration at which the needle valve member (60) blocks a nozzle outlet (16) of the fuel injector (14), and a shoulder (87) of the intensifier piston (80) is exposed to fluid pressure in a common rail (18). The components have a second configuration at which the nozzle outlet (16) is fluidly connected to the common rail (18) for a low pressure injection event (A). The components have a third configuration at which the nozzle outlet (16) is fluidly blocked from the common rail (18), but movement of the intensifier displaces fluid through the nozzle outlet (16) for a high pressure injection event.

Description

Piezoelectricity strengthens fuel injector and uses this piezoelectricity to strengthen the motor of fuel injector

Technical field

Present invention relates in general to have the motor of common rail fuel injection system, more specifically, relate to a kind of piezoelectricity control fuel injector that strengthens piston that is equipped with.

Background technique

In recent years, the compression-ignition prime mover industry begins to recognize that common rail fuel system compares other known fuel system and reduce simultaneously and have some advantage aspect the undesirable effulent improving performance.Undesirable effulent includes but not limited to NOx, hydrocarbon and particulate matter.Common rail fuel system generally includes shared container or the common rail that holds by the fuel of high-pressure service pump pressurization.The single fuel injector of each cylinder is positioned to be used to be directly injected to each cylinder, and via the tributary circuit that separates rail fluid connection individually together.At first, common rail fuel system comprises some automatically controlled adjustable valve systems, its allow each fuel injector any expection engine timing that is independent of crankangle together rail be communicated with, be used for injection event.But this system only limits to the pressure of the fuel in the common rail with regard to jet pressure.

The recent innovation of common rail fuel system is open in the U. S. Patent 6,675,773 of for example authorizing people such as Mahr.This reference teaches is combined in known enhancing piston in the common rail fuel injector.Use the suitably valve of control, this fuel injection system can be as former common rail system from the track direct injection, strengthens piston and sprays under the pressure that raises or strengthen but also can use.Strengthening piston generally includes via the ladder piston realization pressure increase with large surface area and little surface area.The effect of going up of big surface has rail pressure, and the pressure increase of the fuel adjacent with little surface and the area between big surface and the little surface are than proportional.Although this fuel system of describing in 773 patents seems to have realized its purpose, they are not no problem.For example, because various parts pile up the phase mutual interference in a large number in the fuel system, can show difference so seem each identical different fuel sparger.In addition, these system change can also change along with the time.And, the higher jet pressure of always being eager in the industry to seek, it trends towards dissolving in the obviously identical fuel injector controls all other problems relevant with performance variation with fuel injector.At last, all fuel ejection schemes of industrial continuation demand variation, repeatability and reliability more.

The objective of the invention is to above-mentioned one or more problem.

Summary of the invention

On the one hand, fuel injector comprises ejector body, and this ejector body comprises high pressure entry, low pressure drain line and jet expansion.Ejector body comprises nozzle feed path, pin control room and the shoulder control room that is arranged on wherein.First and second electric actuators are positioned at ejector body, comprise piezoelectric pile separately.Strengthen piston and be positioned at slidably in the ejector body, the hydrodynamic pressure in the shoulder control room is born on the shoulder surface of enhancing piston, and between big surface and little surface.Fuel injector also comprises needle valve member, this needle valve member have the hydrodynamic pressure that bears in the nozzle feed path open the hydraulic pressure surface and bear hydrodynamic pressure in the pin control room close the hydraulic pressure surface.Directly the control valve parts are attached to first electric actuator and can move between the primary importance and the second place, wherein at the primary importance place, pin control room fluid is communicated to the low pressure drain line, at second place place, and pin control room and the blocking-up of low pressure drain linear flow body.The enhancing control valve is attached to second electric actuator and can moves between the primary importance and the second place, wherein, at the primary importance place, shoulder control room fluid is communicated to the low pressure drain line, at second place place, shoulder control room and the blocking-up of low pressure drain linear flow body.

On the other hand, motor comprises motor body, wherein is provided with a plurality of cylinders.A plurality of fuel injectors comprise the jet expansion that is arranged to inject directly into difference cylinder separately.Each fuel injector all comprises a plurality of parts.The rail fluid is communicated to each fuel injector altogether.Described a plurality of parts comprise needle valve member, strengthen piston, the first piezoelectric pile electric actuator and the second piezoelectric pile electric actuator.Described a plurality of parts have needle valve member and block first structure that the hydrodynamic pressure in the common rail is born on the shoulder surface of jet expansion and enhancing piston.Described a plurality of parts have the jet expansion fluid and are communicated to second structure that common rail is used for low-pressure fuel injection.Described a plurality of parts have jet expansion together rail fluid blocking-up but strengthen piston mobilely make fluid pass jet expansion to discharge the 3rd structure that is used for high-pressure injection.

Again on the one hand, a kind of method of operating fuel injected system, comprise the steps: by giving rather than two energisings in first electric actuator and second electric actuator, the jet expansion fluid of fuel injector is communicated on the common rail, be used for the low-pressure fuel injection activity.By giving first and second electric actuators both energisings, under from the hydrodynamic pressure that is total to rail, move the enhancing piston, be used for the high-pressure injection activity.By making both outages of first and second electric actuators, make opening the hydraulic pressure surface and closing hydraulic pressure surface both and bear pressure in the common rail of the end that strengthens piston and shoulder surface and needle valve member.

Description of drawings

Fig. 1 is the schematic representation according to motor of the present invention;

Fig. 2 is the plan view of fuel injector according to an aspect of the present invention;

Fig. 3 is the side view of the fuel injector of Fig. 2 of seeing along section line 3-3;

Fig. 3 a is the partial enlarged drawing of Fig. 3;

Fig. 4 is the side view of the fuel injector of Fig. 2 of seeing along section line 4-4;

Fig. 4 a is the partial enlarged drawing of Fig. 4;

Fig. 5 is the side view of the fuel injector of Fig. 2 of seeing along section line 5-5;

Fig. 5 a is the partial enlarged drawing of Fig. 5; And

Fig. 6 is the fuel injection rate time history plot according to several different fuel Spraying rate figures of the present invention.

Embodiment

With reference to Fig. 1, motor 10 comprises common rail fuel injection system 13 and housing 11, is provided with a plurality of cylinders 12 in the housing 11.A plurality of fuel injectors 14 comprise jet expansion 16 separately, and jet expansion 16 is positioned to inject directly in a conventional manner in the different cylinder 12.Each fuel injector 14 all comprises high pressure entry 41, and high pressure entry 41 is via independent tributary circuit 19 rail 18 fluids connection together.Fuel injector 14 also comprises low pressure drain 42, and they all are communicated with the low pressure drain line 25 that enters fuel tank 20.Via the fuel transfer pump (not shown) that is positioned on the low-pressure fuel supply line 21, from fuel tank 20, extract fuel out, be used for to variable displacement high-pressure service pump 22 fuel supplying.Variable delivery pump 22 via communication line 34 controls, so that fuel under high pressure is entered or arranges to being total to rail 18 via high-pressure feed line 24, perhaps makes low-pressure fuel turn back in the fuel tank via reflux pipeline 23 by electronic controller.

Electronic controller 30 is accepted the input signal of various sensors, except the pressure transducer 35 that the relevant pressure information of rail 18 altogether is provided via communication line 31, and other not shown.Described pressure information is used for controlling variable delivery pump 22 by electronic controller 30, so that the pressure that will be total in the rail 18 maintains on some expection level the pressure of for example about 160MPa order of magnitude.Common rail fuel injection system 13 is also controlled by the independent control signal that is fed to each fuel injector 14 via communication line 32 and 33 respectively by electronic controller 30.Although a pair of communication line 32 and 33 only are shown,, it will be understood to those of skill in the art that electronic controller 30 communicates by letter with each fuel injector 14 by a pair of communication line and control each fuel injector 14.It is because each fuel injector 14 comprises first and second electric actuators as described below that two communication lines 32 and 33 are shown.

Referring now to Fig. 2-5, each fuel injector 14 comprises ejector body 40, and it comprises electrical end 43a and the 43b that is connected to communication line 32, and the electrical end 44a and the 44b that are connected to communication line 33.Terminal 43a-b is corresponding with first electric actuator, and terminal 44a is corresponding with second electric actuator with 44b.Each fuel injector 14 comprises multi-part ejector body 40 and various inside is static and movable part and fluid passage.These parts comprise the first piezoelectric pile electric actuator 50 and the second piezoelectric pile electric actuator 51, and they can be structurally identical.Each fuel injector 14 also comprises and strengthens piston 80, strengthen piston 80 comprise with big surperficial 89 with the little surperficial 88 shoulder surfaces 87 that separate.Big surface 89 can be about 2 with little surperficial 88 area ratio, thereby causes considering that the rail pressure after the loss increases about 1.7 times.In addition, a plurality of parts of each fuel injector 14 also comprise direct control needle valve member 60, needle valve member 60 comprise bear hydrodynamic pressure in the nozzle feed path 72 open hydraulic pressure surface 61, and bear hydrodynamic pressure in the pin control room 91 close hydraulic pressure surface 62.The motion of needle valve member 60 is controlled and strengthen moving by the second piezoelectric pile electric actuator 51 of piston 80 by 50 controls of the first piezoelectric pile electric actuator.

Jet expansion 16 is closed by needle valve member 60 usually, and this needle valve member takes a seat under the effect of biasing spring 69 in a conventional manner as shown in the figure, with blocking-up jet expansion 16 and nozzle feed path 72.Between injection event, when first electric actuator 50 and second electric actuator 51 all cut off the power supply, strengthen big surperficial 89, the shoulder surface 87 of piston 80 and little surperficial 88, and the opening hydraulic pressure surface 61 and close hydraulic pressure gauge pressure 62 and all bear common rail fuel pressure between the injection event via following different paths discussed in detail of needle valve member 60.Although first and second

electric actuators

50 and 51 all are piezoelectric pile control, it will be understood to those of skill in the art that, similarly the secondary fuel sparger can also use the solenoid that is used for one or two electric actuator, thereby forms the system that still falls in the scope of the invention.

Specifically with reference to Fig. 3 and 3a, illustrate and the most closely-related various features of control of needle valve member 60 and the details enlarged view of one of them electric actuator now.Each

electric actuator

50 and 51 all comprises piezoelectric pile 52, and piezoelectric pile 52 acts directly on the big piston 53, and big piston 53 hydraulically is attached on the small piston 54 by hydraulic connecting rod 56.Therefore, the elongation of piezoelectric pile 52 and the multiple that shrinks with the ratio of the area between

big piston

53 and 54 increase, and carry out the control function that is associated with fuel injector 14 to produce enough power.Yet, it will be understood to those of skill in the art that and can use replacement scheme, include but not limited to

piston

53 and 54 and the motion multiplier that is associated of hydraulic connecting rod 56 before use one or more flexural piezoelectric machine/curved parts (bender) or bigger piezoelectric pile.First spring 56 is kept contacting between big piston 53 and the piezoelectric pile 52, and second spring 57 is kept small piston 54 and direct contacting between the control valve parts 100.The various internal paths of passing piezoelectric pile electric actuator 50 are kept between the action of hydraulic connecting rod 56 suitably filling fuel.It will be understood to those of skill in the art that the distance of piezoelectric pile 52 elongation and directly the corresponding sports distance of control valve parts 10 is proportional with the voltage that is applied on the piezoelectric pile 52 by terminal 43a and 43b in a conventional manner.

When 50 outages of the first piezoelectric pile electric actuator, directly control valve parts 100 are made progress bias voltage to close conical seat 103 by spring 101, are communicated to the low-pressure passage 47 of floss hole 42 with blocking-up pin control room 91 and fluid.High pressure entry 41 is communicated to nozzle feed path 72 via track injection line 70 direct fluids.Safety check 71 prevents that fuel from going into track injection line 70 from nozzle feed path 72 reverse flow, for example when strengthening piston 80 and carry out the high-pressure injection activities.Pin control room 91 always via the high-pressure passage 67 that comprises metering hole 67a without barrier fluid be communicated to nozzle feed path 72.When the outage of first electric actuator 50 makes that direct control valve parts 100 are in the upper position of closing conical seat 103, pin control room 91 also via path 65 and vent pathway 66 through flat seats 102 and fluid is communicated on the nozzle feed path 72.Path 65 comprises the metering hole adjacent with flat seat 102 as shown in the figure, and vent pathway 66 also comprises metering hole equally as shown in the figure, and it is adjacent that this metering hole and vent pathway 66 are led to the position in pin control room 91.Although optional, when needle valve member 60 is moved upward to its open position when opening jet expansion 16, the size and the Position Design of the individual channel relevant and be arranged to form hydraulic pressure backstop with pin control room 91.This is by giving 50 energisings of first electric actuator to move down direct control valve parts 100 to close flat seat 102 and to open conical valve seat 103 and realize.Via vent pathway 66 pin control room 91 fluids are communicated to floss hole 42 like this.

Along with needle valve member 61 rises, its part of closing hydraulic pressure surface 62 forms flow restriction portion at the position of leading to vent pathway 66.This flow restriction portion is inevitable greater than the 67a of flow restriction portion, so that needle valve member 60 is hovered when limiting the contacting of formation path 67 and 66 fuel injector parts just in time breaking away from.It will be understood to those of skill in the art that when needle valve member 60 is in it and makes progress open position, be communicated with forming direct fluid altogether between rail 18 and the floss hole 42.But, with respect to existing fuel injection system, by adopting hydraulic pressure backstop, reveal by strict restriction, this hydraulic pressure backstop has been improved the reactivity of needle valve member 60, has also reduced other sum of errors simultaneously and has made the amount of leakage minimum, and therefore made the energy dissipation minimum that is associated with execution control function.When first electric actuator 50 disconnected with the end injection activity, spring 101 upwards promoted direct control valve parts 100 to close conical seat 103.This causes pin control room 91 to be communicated with via high-pressure passage 67 and via path 65 and vent pathway 66 high-pressure liquids unexpected and in the nozzle feed path 72, exports 16 with downward fast moving needle valve member 60 with shut-off nozzle.Therefore, by giving 50 energisings of the first piezoelectric pile electric actuator and outage, can carry out relatively low pressure fuel injection event from being total to rail 18.

Referring now to Fig. 4,4a, 5 and 5a, illustrate with by moving the various features that strengthen the relevant fuel injector 14 of high-pressure injection activity that piston 80 realizes.Strengthen piston 80 and comprise plunger 81, plunger has little surperficial 88 and elongate rod 82.The collar 83 is assemblied on the bar 82, thereby limits a part and the shoulder 87 that forms big surface 89.Retaining washer 84 is assemblied on the ejector body 40, as the platform that is attached to the Returnning spring 86 of bar 82 via the packing ring 85 that resets.Therefore, Returnning spring 86 will strengthen piston 80 and upwards be biased into as shown in the figure retracted position.Shoulder 87 bears the hydrodynamic pressure in shoulder control room 90.By stopping and activating the second piezoelectric pile electric actuator 51, pressure or fluid that shoulder control room 90 fluids are communicated in the common rail 18 are communicated to low pressure drain 42, control to strengthen moving of piston 80.Strengthen moving down of piston 80 and cause being displaced in the nozzle feed path 72, leave jet expansion 16 during for the high-pressure injection activity with little surperficial 88 adjacent fuel.Shoulder control room 90 is communicated to communication chamber 79 via shoulder path 76 fluids.And then via flat seated valve parts 114 and low-pressure passage 46 blocking-up, wherein, low-pressure passage 46 fluids are communicated to floss hole 42 to communication chamber 79 usually, and flat seated valve parts 114 are in normal contact condition to close flat seat 112.Biasing spring 111 is biased into flat seated valve parts 114 simultaneously to contact with flat seat 112 and will strengthen control valve parts 110 and is biased into conical valve seat 113 and contacts.It should be noted that to strengthen control valve parts 110, and direct control valve parts 100 previously discussed, all comprise circle or spherical valve surface, even this helps also can take a seat better respectively with under the situation of conical valve seat 113 and 103 misalignment.Flat seated valve parts 114 also comprise the control surface 117 that bears hydrodynamic pressure in the enhancing control room 115.In the time of on strengthening the conical seat 113 that control valve parts 110 sit in as shown in the figure, blocking-up strengthens control room 115 and leads to low-pressure passage 116 and floss hole after this 42.But, strengthen control room 115 always via pressure communication path 119, pressure communication path 118 and directly fluid be communicated to the shoulder reset paths 75 of high pressure entry 41 and fluid is communicated on the common rail 18.Pressure communication path 118 comprises metering hole 118a, and it and aforementioned mouthful of 67a work in a similar manner.Especially, the pressure that strengthens in the control room 115 will keep high level, up to causing flowing through the flow area of conical seat 113 greater than the flow area that passes mouthful 118a via the motion that strengthens control valve parts 110.When the pressure in strengthening control room 115 reduces, act on the pressure higher on the lifting hydraulic pressure surface 129 and push away flat seated valve parts 114, to open flat seat 112.Via communication chamber 79 and shoulder path 76 shoulder control room 90 fluids are communicated to low-pressure passage 46 like this.After these were finished, the pressure on the shoulder 87 was released, and rail pressure act on strengthen piston 80 big surperficial 89 on, strengthen piston with downward driving.This can recently increase the pressure in the nozzle box 72 according to the area of enhancing piston 80, and closes safety check 71 between active stage at high pressure, thereby makes nozzle box 72 rail 18 fluids blocking-up together.But strengthening moving of piston will can not continue, because strengthen the mobile by the hydraulic pressure locking of piston, unless needle valve member 60 is shown in an open position to allow fuel to discharge via jet expansion 16.Therefore, by moving to upwards open position to allow needle valve member 60 for 50 energisings of first electric actuator, and the pressure of discharging on the shoulder surface 87 for 51 energisings of second electric actuator driven downwards and is used for the high-pressure injection activity to allow to strengthen piston 80, realizes the high-pressure injection activity.

Referring now to Fig. 5 and 5a, illustrate and allow to strengthen piston 80 resets to the fuel injector 14 of its retracted position between injection event various features.Especially, by making first and second

electric actuators

50 and 51 outages come initial reset phase place/state (phase).After these are finished, strengthen control valve parts 110 and under the effect of spring 111, move up to close conical valve seat 113.The fluid that this has closed (disconnection) between enhancing control room 115 and the low-pressure passage 116 is communicated with.Therefore, high pressure turns back to enhancing control room 115 and acts on the control surface 117 with spring 111, and flat seated valve parts 114 are moved down to close flat seat 112.When the inner member of fuel injector was in this structure, biasing spring 122 biased downward resetted valve member 120 opening valve seat 121, thus with shoulder path 76 through valve seats 121 and fluid is communicated on the shoulder reset paths 75.This fluid is communicated with the fuel that allows from being total to rail 18 and flows downward, and passes shoulder path 76 and enters communication chamber 79, through valve seat 121, and finally arrives shoulder control rooms 90 via shoulder reset paths 75.These fluids are communicated with to strengthen the hydraulic pressure on the piston 80 balanced basically, upwards shrink under the effect of Returnning spring 86 thereby allow to strengthen piston 80, are used for the post-injection activity.Preferably, the preloading on the various end surfaces 124,125 of valve member 120 and the biasing spring 122 that reset is selected to, make not contact when being communicated to communication chamber 79 fluids in the low-pressure passage 46 when flat seated valve parts 114 that the valve member 120 that resets moves up to close valve seat 121 with flat seat 112.In the high-pressure injection active procedure, the pressure that acts on the communication chamber 79 on the hydraulic pressure surface 124 is enough high, thereby can overcome preloading on the downward hydraulic coupling that acts on the hydraulic pressure surface 125 and the spring 122, to close leakage paths in the injection event process.The hydraulic pressure surface 124,125 and the preloading of spring 122 of valve member 120 and meticulous adjusting thereof of resetting is used to avoid being provided with another electric actuator, thereby helps the fuel injector 14 that resets between injection event.

Industrial applicibility

The present invention has found the potential application in any common rail fuel injection system.Fuel injector of the present invention has been found the special application in the compression-ignition motor.Between injection event,

electric actuator

50 and 51 all is de-energized.Under this structure, jet expansion 16 gets clogged, and simultaneously needle valve member 60 opens hydraulic pressure surface 60 and close hydraulic pressure surface 62 and bear rail pressure.Strengthen piston 80 transfixions and with act on big surperficial 89, little surperficial 88 and shoulder surface 87 on rail pressure hydro-cushion basically.

With reference now to Fig. 1,3,3a and Fig. 6,, by giving 50 energisings of the first piezoelectric electro actuator and outage, allow the second piezoelectric electro actuator 51 cut off the power supply simultaneously, realize the movable A of low-pressure fuel injection.In the present invention, the low-pressure fuel injection activity occurs under the extreme high pressure, for example 160MPa or the above order of magnitude, but compare low with using the more high-pressure injection activity that strengthens piston 80.In the low-pressure fuel injection active procedure, jet expansion 16 is communicated on the common rail 18 by nozzle feed path 72 and track injection line 70 direct fluids.In the movable beginning of the low-pressure fuel injection of expection not long ago, the first piezoelectric pile electric actuator 50 was energized.When it extended, pin control valve parts 100 began to move and contact with conical seat 103, by vent pathway 66 and low-pressure passage 47 pin control room 91 fluids are communicated to floss hole 42.After these are finished, pressure in the pin control room 91 reduces, can overcome preloading of the residual solution pressure of closing on the hydraulic pressure surface 62 and spring 69 thereby allow to open high-pressure on the hydraulic pressure surface 61, thereby allow needle valve member 60 to move up to open jet expansion 16.Although it is not essential to the present invention,, various pipeline facilities can be provided for forming the hydraulic pressure backstop of needle valve member 60.This is by blowdown piping 66 is realized being arranged to lead to pin control room 91 with the position of closing 62 interferences of hydraulic pressure surface.In other words, close that hydraulic pressure surface 62 will move up and hover when limiting the parts that form vent pathway 66 just in time breaking away from, form flow restriction thereby limit, this flow restriction has the big flow area of fluid restriction 67a than the high pressure that pin control room 91 fluids is communicated to nozzle feed path 72.The structure of various parts in the fuel injector 14 when this has described the low-pressure fuel injection activity.Described injection event is by 50 outages finish to the first piezoelectric pile electric actuator.After these were finished, biasing spring 101 upwards promoted pin control valve parts 100 to close conical valve seat 103, opens flat valve seat 102 simultaneously.Via high-pressure passage 67 and via path 65 and vent pathway 66 pin control room 91 unexpected fluids are communicated to the high pressure of nozzle feed path 72 like this, with the pressure in rising pin control room 91.This can cause needle valve member 60 hydro-cushion substantially, thereby allows biasing spring 69 to promote needle valve member 60 downwards with shut-off nozzle outlet 16, end injection activity.In the low-pressure fuel injection active procedure, strengthen piston 80 and keep transfixion.

Referring now to Fig. 1,4,4a and 5,5a and 6, switch on by at first giving second electric actuator 51, and carry out the square injection event B of high pressure for soon after 50 energisings of first electric actuator.By giving the second piezoelectric pile electric actuator 51 energisings, the pressure in the shoulder control room 90 is released, and enhancing piston 80 is driven downwards.But, be energized up to first electric actuator 50 owing to needle valve member 60 remains on its downward closed position, so strengthen piston 80 by the hydraulic pressure locking.But the pressure in the nozzle feed path 72 will and strengthen little surperficial 88 and the ratio of the area between the surface 89 increase pro rata greatly of piston 80.Therefore, act on this moment and open hydraulic pressure surface 61 and close fuel pressure on the hydraulic pressure surface 62 and may just in time be higher than pressure in the common rail 18.Then, when first electric actuator 50 is energized when discharging the pressure in the pin control room 91, needle valve member 60 fast moving to be to open jet expansion 16, make it bear the pressure of rising fully in the nozzle feed path 72.This causes the Spraying rate of the almost vertical lifting shown in curve B among Fig. 6.Thereby by give 50 outages of first electric actuator move down needle valve member 60 with shut-off nozzle outlet 16 end injection activity B.

By giving first and second

electric actuators

50 and 51 energisings substantially simultaneously, can carry out gradient injection event C.When this happens, needle valve member 60 is moved upwards up to open position to open jet expansion 16, simultaneously it moves down and begins upwards to increase from the pressure of track 18 pressure along with strengthening piston 80 beginnings, and finally with Spraying rate like the square injection curve category-B previously discussed under tend to be steady.By giving 50 energisings of first electric actuator earlier and giving second electric actuator 51 energisings after a period of time, fuel injector 14 can also produce multiple boot-shaped injection curve D or E.When this situation took place, Spraying rate will begin to be elevated to the maintenance level of the pressure correlation connection of rail 18 together, then in 51 energisings of second electric actuator with increase soon after beginning to strengthen the moving down of piston 80.Therefore, the Spraying rate curve D will make second electric actuator 51 more approach first electric actuator 50 than Spraying rate curve E in time to be energized.All high-pressure injection activities are characterised in that to move and strengthen piston and give

actuator

50 and 51 boths energisings.

Fuel injector 14 also comprises by giving 51 energisings of second electric actuator and outage and giving 50 energisings of first electric actuator and/or outage and change the ability of jet pressure during injection event.For example, make 51 outages of second electric actuator by keeping 50 energisings of first electric actuator, the injection of carrying out in the injection event process under one the 3rd pressure is feasible.Strengthening under the piston 80 contractions situation that needle valve member 60 stays open simultaneously, the 3rd jet pressure is feasible.Finally, shrink fully if strengthen piston, Spraying rate will return to direct from being total to the corresponding Spraying rate of injection curve A that rail 18 sprays.Thereby by selecting the timing of second electric actuator 51 energising with respect to 50 energisings of first electric actuator, fuel injector 14 also has correction Spraying rate ability in the middle of some and when finishing (end).This ability of regulating jet pressure in the injection event process is newer ability for fuel injection system, has showed a kind of new method that can reduce effulent and/or increase feasibility.

Another unconspicuous be characterised in that relevant with fuel injector 14 regulated the rate travel that strengthens piston by the energising voltage of regulating on the second piezoelectric pile electric actuator 51, can regulate the gradient of front end ramp rate shape in the injection event thus.In other words,, flow area can be regulated, and the pressure that strengthens control room 115 can be controlled thus through valve seat 113 by regulating the voltage on the second piezoelectric pile electric actuator 51.This so regulated power on the flat seated valve parts 114, thereby accurately control flows is through the flow area of flat seat 112, thereby the control fluid can be from the shoulder control room 119 speed of discharging, and therefore control strengthens the rate travel of piston 80.Certainly, strengthen the rate travel of piston 80 and then the pressure in control nozzle feed path 72 and the jet expansion after this 16.Therefore, different with solenoid electric valve, valve of the present invention can be located at an arbitrary position to stop according to the certain voltage that is applied on the piezoelectric pile electric actuator.Although very possible is, the precise voltage that produces certain effect in a sparger may be different with the voltage that seems identical fuel injector, but it will be understood to those of skill in the art that the performance difference between the fuel injector can use known electronics finishing strategy to alleviate.

Should be appreciated that top explanation only is used for exemplary purpose, scope of the present invention is not had any limited significance.Therefore, it will be understood to those of skill in the art that by research accompanying drawing, specification and claims and can obtain others of the present invention, purpose and advantage.

Claims

1. a fuel injector (14) comprising:

Ejector body (40), this ejector body comprise high pressure entry (41), low pressure drain line (25) and jet expansion (16), and comprise nozzle feed path (72), pin control room (91) and shoulder control room (90) that are arranged in the ejector body;

Be positioned at first electric actuator (50) that comprises piezoelectric pile (52) of ejector body (40);

Be positioned at second electric actuator (51) that comprises piezoelectric pile (52) of ejector body (40);

Be positioned at the enhancing piston (80) in the ejector body (40) slidably, the hydrodynamic pressure in the shoulder control room (90) is born on the shoulder surface (87) of this enhancing piston, and is positioned between big surface (89) and little surface (88);

Needle valve member (60), this needle valve member have the hydrodynamic pressure that bears in the nozzle feed path (72) open hydraulic pressure surface (61) and bear hydrodynamic pressure in the pin control room (91) close hydraulic pressure surface (62);

Direct control valve parts (100), these direct control valve parts are attached to first electric actuator (50) and can move between the primary importance and the second place, wherein, at the primary importance place, pin control room (91) fluid is communicated to low pressure drain line (25), at second place place, pin control room (91) and the blocking-up of low pressure drain line (25) fluid;

Strengthen control valve (110,114), this enhancing control valve is attached to second electric actuator (51) and can moves between the primary importance and the second place, wherein, at the primary importance place, shoulder control room (90) fluid is communicated to low pressure drain line (25), at second place place, and shoulder control room (90) and the blocking-up of low pressure drain line (25) fluid.

2. fuel injector according to claim 1 (14), it is characterized in that: strengthen control valve and comprise control valve parts (110) and flat seated valve parts (114), described control valve parts contact with second electric actuator (51), and described flat seated valve parts have the control surface (117) that bears the hydrodynamic pressure in the enhancing control room (115);

Described control valve parts (110) can move between primary importance and second, wherein, at the primary importance place, strengthen control room (115) and the blocking-up of low pressure drain line (25) fluid, at second place place, strengthen control room (115) fluid and be communicated to low pressure drain line (25); And

Described flat seated valve parts (114) can the primary importance that contacts with valve flat seat (112) and and the discontiguous second place of valve flat seat (112) between move.

3. fuel injector according to claim 2 (14), it is characterized in that: described flat seated valve parts (114) have the continuum of diverse location between the primary importance and the second place, separately corresponding to the different flow areas that strengthen between control room (115) and the low pressure drain line (25); And

The continuum of each diverse location is corresponding to the different voltages on the piezoelectric pile (52) of second electric actuator (51).

4. fuel injector according to claim 1 (14) comprises and keeps the accessible path (65) that fluid is communicated with between common rail (18) and pin control room (91);

The vent pathway (66) of when a certain position, leading to pin control room (91), wherein, close hydraulic pressure surface (62) limit fluid vent pathway when pin control room (91) flow into low pressure drain lines (25) simultaneously and form hydraulic pressure backstop when needle valve member (60) is shown in an open position in this position.

5. fuel injector according to claim 1 (14), comprise the sparger that can between the primary importance and the second place, the move valve member (120) that resets, wherein, at the primary importance place, shoulder control room (90) fluid is communicated to common rail (18), at second place place, shoulder control room (90) rail (18) fluid blocking-up together.

6. fuel injector according to claim 1 (14) is characterized in that: directly control valve parts (100) contact with first electric actuator (50);

Control valve parts (100) do not contact with flat seat (102) will be total to rail (18) fluid at second place place and are communicated with pin control room (91); And

Control valve parts (100) contact with flat seat (102) will be total to path (65) the fluid blocking-up between rail (18) and pin control room (91).

7. a motor (10) comprising:

Motor body (11) is provided with a plurality of cylinders (12) in this housing;

A plurality of fuel injectors (14) comprise the jet expansion (16) that is arranged to inject directly into difference cylinder (12) separately, and each fuel injector (14) all comprises a plurality of parts;

Fluid is communicated to the common rail (18) of each fuel injector (14);

Described a plurality of parts comprise needle valve member (60), strengthen piston (80), the first piezoelectric pile electric actuator (50) and the second piezoelectric pile electric actuator (51);

Described a plurality of parts have needle valve member (60) and block first structure that the hydrodynamic pressure in the common rail (18) is born on the shoulder surface (87) of jet expansion (16) and enhancing piston (80);

Described a plurality of parts have jet expansion (16) fluid and are communicated to second structure that common rail (18) is used for low-pressure fuel injection; And

Described a plurality of parts have jet expansion (16) together rail (18) fluid blocking-up but strengthen piston (80) mobilely make fluid pass jet expansion (16) to discharge the 3rd structure that is used for high-pressure injection.

8. the method for an operating fuel injected system (13) comprises the steps:

By giving rather than two energisings in first electric actuator (50) and second electric actuator (51), jet expansion (16) fluid of fuel injector (14) is communicated on the common rail (18), be used for low-pressure fuel injection activity (A);

By giving first and second electric actuators (50,51) both energisings, under from the hydrodynamic pressure that is total to rail (18), move enhancing piston (80), be used for the high-pressure injection activity; And

By making first and second electric actuators (50,51) both outages, make opening hydraulic pressure surface (61) and closing hydraulic pressure surface (62) both and bear pressure in the common rail (18) of the end (88,89) that strengthens piston (80) and shoulder surface (87) and needle valve member (60).

9. method according to claim 8 is characterized in that: mobile step comprises by the energising voltage of the piezoelectric pile of regulating second electric actuator (51) (52) regulates the rate travel that strengthens piston (80).

10. method according to claim 9 is characterized in that: regulating step comprises the pressure that changes in the enhancing control room (115); And

Make flat seated valve parts (114) bear the hydrodynamic pressure that strengthens in the control room (115).